Science - Pain receptors in the bowels

The intestines are lined with sensory neurons that detect stimuli, including pain. These pain receptors, known as nociceptors, are located in the walls of the intestines, as well as in the surrounding tissues and organs. 

When the intestines are damaged or irritated, the nociceptors send signals to the brain, which interprets them as pain. This can occur due to a variety of factors.

Qur'an - Pain receptors in the bowels

مَّثَلُ ٱلْجَنَّةِ ٱلَّتِى وُعِدَ ٱلْمُتَّقُونَ فِيهَآ أَنْهَـٰرٌ مِّن مَّآءٍ غَيْرِ ءَاسِنٍ وَأَنْهَـٰرٌ مِّن لَّبَنٍ لَّمْ يَتَغَيَّرْ طَعْمُهُۥ

 وَأَنْهَـٰرٌ مِّنْ خَمْرٍ لَّذَّةٍ لِّلشَّـٰرِبِينَ وَأَنْهَـٰرٌ مِّنْ عَسَلٍ مُّصَفًّى وَلَهُمْ فِيهَا مِن كُلِّ ٱلثَّمَرَٰتِ

 وَمَغْفِرَةٌ مِّن رَّبِّهِمْ كَمَنْ هُوَ خَـٰلِدٌ فِى ٱلنَّارِ وَسُقُوا۟ مَآءً حَمِيمًا فَقَطَّعَ أَمْعَآءَهُمْ

(Here is) a Parable of the Garden which the righteous are promised: in it are rivers of water incorruptible; rivers of milk of which the taste never changes; rivers of wine, a joy to those who drink; and rivers of honey pure and clear. In it there are for them all kinds of fruits; and Grace from their Lord. (Can those in such Bliss) be compared to such as shall dwell for ever in the Fire, and be given, to drink, boiling water, so that it cuts up their bowels (to pieces)? 47:15

The above verse indicates that drinking boiling water causes such a excruciating pain in the bowels that feels like they are being cut.  No one knew 1400 years ago that the pain will be originating from the bowels.